Projection video display devices such as a liquid crystal projector irradiate a display element such as a liquid crystal panel with light emitted from a light source such as a mercury lamp, and enlarges and projects a video formed by the display element with a projection lens onto a screen. The configuration of an optical system of the device includes an optical unit from irradiation with light emitted from the light source on the liquid crystal panel to formation of the video (hereinafter, referred to as an optical engine) and a projection optical system which enlarges and projects the video formed by the liquid crystal panel with the projection lens. In an optical engine of a color video display device, three liquid crystal panels for three primary colors (RGB) as display elements, a color separation system for irradiation light, and a color synthesis system for respective video colors are provided. Moreover, for adjusting a video-displaying position on the screen, a lens shifting mechanism is provided in the projection optical system which can move a projection lens in a direction perpendicular to an optical axis.
The optical engine and the projection optical system are positioned with respect to each other and are accommodated in a case of the device. In a conventional accommodating method, as described in Patent Literature 1, for example, respective components of the optical engine including the light source are accommodated and arranged in a light guide as an optical components case, and the light guide is fixed to the case of the device. The projection optical system is configured to be joined and fixed to an outgoing end portion of the light guide.